ok. yeah. pursuing that, i'm wondering if there's a simple way to convince someone that this is true.
one idea I saw somewhere was that because awk is part of a Turing complete language, it can be used to implement the relational algebra. though I don't know how to prove that myself, except by actual construction: implementing each part of the relational algebra definition.
looking over the definition of relational algebra, at first I wondered: what about a theta join? it's not directly built into the CLI "join" command. but then the article points out that if you can obtain a Cartesian product of two tables then you can use a Select to filter out the rows that do not meet the criteria of your theta join.
and then there's division, which I can only guess would depend heavily on some careful awk scripting.
and so it goes. IDK. it seems a bit laborious to prove it all by construction.
